The overall objectives of this project are to produce and characterize relevant Aspergillus fumigatus (Af) antigens for early diagnosis of Aspergillus and to understand the immunopathogenesis of allergic aspergillosis. Allergic bronchopulmonary aspergillosis (ABPA) is a destructive lung disease frequently occurring in atopic individuals and in cystic fibrosis patients. The diagnosis of the disease is based mostly on immunological criteria, yet our understanding of the immunodiagnosis and immunopathogenesis of this disease is unsatisfactory. Furthermore, due to the lack of reliable reagents and inconsistent reproducibility of assays, the interpretation of the test results are frequently difficulty and less contributory and has been cited as a major reason why more patients are not diagnosed during the early onset of the disease. Four pure antigens from Af obtained through molecular cloning have been identified and all of them demonstrated significant IgE antibody binding and T-cell proliferation activities in ABPA. Both in vitro and in vivo tests will be used to demonstrate Af specific IgE antibodies in the sera of patients using the four recombinant Af antigens. The epitopes binding to IgE will be identified and compared with other known allergens and unique ones will be cloned and expressed. These cloned epitopes bearing polypeptides will be evaluated for their specificity and relevancy in the diagnosis of ABPA. T-cells from ABPA patients will be cloned for understanding the mechanism of the disease by studying the Th1 and Th2 cytokine profile. T-cell lines generated against Asp f2 will be stimulated with synthetic peptides from the sequence of Asp f2, a recombinant protein with reactivity with ABPA< and T-cell epitopes will be identified. The cytokines produced by these clones in response to synthetic T-cell epitopes will be assessed to understand the pathogenesis of the disease. The cytokine profile will add to our knowledge on the pathophysiological events associated with disease. The results of these studies will provide the much needed understanding of the immune mechanism active in ABPA, which in future can be used to control or manage the disease effectively.